While there have been many studies of dental anxiety, there remain significant gaps in our understanding of its development and course. Its prevalence in adults, differences according to gender, the characteristics of dentally anxious individuals, changes in dental anxiety with aging and trends over time all require further investigation. Data concerning these issues is important in training dental care providers to prevent, identify and manage appropriately the problem posed by dental anxiety. This project consists of a longitudinal study, the baseline phase of which aims to a) measure the prevalence of dental anxiety in the adult population using different scales and cut-off points; b) determine the effect on prevalence estimates, overall and by gender, by using these measures; c) determine the prevalence of the four diagnostic categories describe by Milgrom et al (1985), overall and by gender; d) assess the utility of this diagnostic system in terms of the criteria described by Sheehan and Sheehan (1983) of uniqueness and internal consistency; e) describe the characteristics of females and males in each category according to the three-systems model of dental anxiety; and f) assemble a panel for longitudinal study. Data will be collected by means of two four-wave mail surveys. The first will consist of a screening questionnaire sent to 5000 randomly selected adults living in Metropolitan Toronto and will identify individuals with different degrees of dental anxiety from no fear to phobic. The second will consist of a more detailed questionnaire, consisting of measures of psychological characteristics, and will be sent to all responders to the first phase who agree to participate further in the study. This approach has been selected in order to maximize the overall response. Further follow-ups of these responders and newly selected samples will take place in five and ten years. Contact will be maintained with subjects between survey periods to minimize attrition over time.